<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8" />
    <meta http-equiv="X-UA-Compatible" content="IE=edge" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <title>promise基本语法</title>
  </head>

  <body>
    <script>
      //实例化 Promise 对象
      //resolve 数据读取成功      reject 数据读取失败
      const p = new Promise(function (resolve, reject) {
        setTimeout(function () {
          //   let data = "数据库中的用户数据";
          //   resolve(data);

          let err = "数据读取失败";
          reject(err);
        }, 1000);
      });

      //调用promise 对象中的then方法
      p.then(
        function (value) {
          console.log(value);
        },
        function (reason) {
          console.error(reason);
        }
      );
    </script>
  </body>
</html>
